Prius, real science or marketing stragegy?

Here's an easy solution -- read the article referenced in this thread.

It's an extremely short and well-written article on the technical nutshell of why the Prius works so well. It's got a "smart engine" -- it runs on electricity or gas when it's most efficient to do so. The Prius gets very good gas mileage because the ICE runs only when it can do so most efficiently.

It's not the body of the Prius -- the Prius is actually a fairly heavy car for the size, I believe (mostly the battery).

I would show this article to your science teacher -- it says it better than I can.

 

To put it bluntly, his response is just plain wrong.


> the body of the car is so light that it gets 50mpg

Prius weighs 785 pounds *MORE* than Echo. So the theory about weight reduction is clearly incorrect.


> Without greater knowledge about how good today’s battery technology is up to, I can not argue his point.

His focus on battery technology is the problem. Force him to look at the big picture instead. Then it becomes simple.

Prius has a smaller-than-average engine. That alone is all that is really needed for a rebuttal. Today's modern gas engine is grossly oversized for the amount of horsepower actually required to propel you down the road. The HSD design simply takes advantage of that fact, by having an engine closer to the size that is actually needed for sustained cruises. Extra power comes from the electric motor, used only at times when it is more efficient than the engine can deliver.

That size difference and offloading to the motor results in a very noticeable gas savings.

 

I am really glad for Scotty's uninformed science teacher. Without him we probably would never have been shown the wonderfully detailed context for our cars. Thanks to people like Bookrats and John, we all seem to know what we have. Thanks to you guys, you have both helped me a lot even before the above string.

 

if getting 500 miles to an 11gallon tank is not a sign of saving gas then i don't know what is. i wonder what he'd consider saving gas? and what does he know about the battery recharge in a prius..? from what he said..... not much!

 

I agree that you should show him the article Jeff referenced. Also consider these:

• There is a LOT more to the Prius than regenerative braking.

 

<div class='quotetop'>QUOTE(eak354\";p=\"91577)</div>

Unless you have a 30 gallon tank then some vehicles could get 500 miles on a tank :mrgreen:

 

As Einstein said, "what exists is possible". The science teacher should follow Einstein's dictum before spouting off about the Prius. It's awfully nice that everyone is so polite here, but I would expect that a science teacher would have taken the time to at least learn some of the basics, like weight, about the Prius.

Not only is the Prius heavier than the Echo, it's over 150 pounds heavier than the Honda Hybrid, yet gets better performance and gas mileage. The proof is in the pudding.

 

Scotty,

Change classes QUICK!

If this guy is teaching you Science, then you're in the wrong class. No TRUE scientist would make such blatantly WRONG statements without checking facts.

As stated before - Prius is NOT a "light weight" vehicle. This is NOT how it manages fuel economy. It manages great gas mileage because it is THE current technological answer in proper use of an internal combustion engine. By mixing the ICE with proper computer-controlled electrical power, the Prius achieves not only great gas mileage, but really great emmissions ratings as well.

Ask your teacher what kind of mileage that Echo is getting when it's sitting at the light with it's engine running, next to the Prius that isn't burning an ounce of gas awaiting green.

8)

Yoda

 

<div class='quotetop'>QUOTE(ScottY\";p=\"91566)</div>

Others have made comments better than I could, but I'd like to add that your friend's comment assumes that all the energy that an ICE produces goes into making the car move forward and that charging the battery steals some of that energy. That's an incorrect assumption. In fact a very large portion of the energy that an ICE makes is wasted. Hybrids use that waste to make electricity, and stores it in the battery. And the regen brakes only recaptures one of many areas of that waste. The ICE does sometimes (rarely) work only to make electricity, but that is rare. Most of the electricity comes from otherwise wasted energy.

Yes, it may only be able to store 50% (or some other percent) of that wasted energy, but without the batteries, you are losing 100% of that energy.

And keep in mind, this technology is in it's infancy. So buy a Prius in 2005 and get a car that is super clean and fun to drive. And at the same time, you will be helping move that technology into it's adolescence. And as for price, the gas savings will make it either cheaper if you keep if for awhile (5+), or only slightly more expensive if you trade it in real soon. (2+).

 

Hey ScottY-
what is this about 50 MPG? I almost never get 50 MPG. In fact the current tank is at 530 miles with three bars still showing on the gas gauge. The display is showing a mere 60.1 MPG. I'll probably have to get gas before I even get to 800 miles on the tank. Your teacher is right. There's nothing to this car. It's just a scam.

Actually regen braking is only responsible for a 1-2 MPG increase.

 

<div class='quotetop'>QUOTE(lgeisz\";p=\"91603)</div>

haha noted and edited! :mrgreen:

 

<div class='quotetop'>QUOTE(Ray Moore\";p=\"91620)</div>

50 is the best I get in the long run, i.e., half a tank or so. How do you drive so that you get 60?

 

How one could possibly average 60MPG over a whole tank, I have no idea. Ray must have a very odd commute.

Perhaps if every trip was a 40-minute 30mph cruise, I might just manage 60MPG US. I'm currently averaging 45.8 (US) by the display, 44.4 (US) by measurement.

I'm lucky to sustain 50MPG (US) on any motorway cruise at 60mph. With a tailwind I might manage 55MPG for a short while.

I wonder if anyone has any idea how the efficiency of the US vs European Priuses compare. I'd imagine we lose due to bigger wheels, wider tyres and no coolant storage.

 

Too late to really pop off on this thread, ScottY... but your friend... the science teacher, well, I'm afraid... geez it pains me to say this...

he's an idiot.

Sorry.

 

My commute goes like this.

Two miles slight climb at 30mph during warmup.
Two miles slight descent at 40mph in neutral.
Two miles rolling hills climbing mostly at 45mph on back roads.
Two miles through small town at 45-50mph.
Twenty-two miles of highway driving at 60-70mph. Usually catch at least six redlights at highway speeds which I anticipate to avoid coming to a complete stop.
Four miles in town thrugh neiborhoods at 20-40mph.

I usually get passed by the same car multiple times and pass them back at each redlight. I have used neutral to great effect in certain situations, averaging twelve miles spent in neutral during the complete round trip. I travel a different route coming home and it is similar so I won't post the details of it except to say that the speeds going home are mostly 55-65mph.

I actively drive the car. If I drive conservatively but without paying attention and use cruise control, I get about 5 MPG less. My wife uses mega-AC and drives about 5mph faster than me. She uses neutral about half as much as me and does not think about mileage much beyond that. She is averaging 50-51 MPG. Her driving style has changed and she is less agressive than she was in her SUV. Less stressed on arrival as well.

 

12 miles in a round trip in N - out of 68 ?! Wow. I have *never* used N with my Prius. Only D. In what situations do you use N?

 

Back roads with no traffic and flat to slight descent. Approaching red lights or stale green lights from far out with no close traffic. Downhill stop and go at <8 mph where I am mostly riding my brakes and don't want the electric motor to be trying to inch the car forward against the brakes. Anywhere you would try to coast with the peddle feathered to a no arrow condition, I will slip it into neutral, when safe to do so. I don't do it above 62mph in my 04. It is easier than feathering for long distances. It's just second nature now, like driving a standard part of the time.

 

Ray it may be the terrain you drive in combined with your driving style. I do not do anything special but I do drive it like my old F250 (rarely go above 60 mph, brisk accel to speed then cruise, avoid using brakes - coast alot, etc) and get about 54 mpg. My wife's driving style is opposite of mine. She gets an avg of 48. This is calculated by hand calculations. The MFD usually shows me higher than hand calc.